For the past 10 years or so, I have been sorcing UHMW polyethylene from manufacturers, packaging the pieces in assortments and selling them through woodworking distributors like Lee Valley and Woodcraft. I have noticed that the sales at Woodcraft don't seem to be on a par with the sales in Canada (they're lower) and I wonder why that is. I have some huge new supplies available of UHMW and I'm looking to expand sales. I have noticed that some of the other woodworking distributors either don't sell UHMW and those that do don't seem to carry much of it. I have noticed that Ebay and Amazon.com have sellers of UHMW on them.
My questions are - Those of you that buy UHMW, where do you get it? - If you could get offcuts of UHMW at a good price on Ebay, would you buy it there?
Be careful with Machinist Materials in Florida, they sell a lot on eBay. I purchased 2 lots thinking that I would benefit from a consolidation of the order into one shipment based on a cursory review of their shipping policies. I was charged and paid $20.20 for Fedex delivery. When the parcel arrived, I measured and weighed it before opening and then visited Fedex's site which quoted me $14.43 -- that's withough any discount a regular shipper may enjoy. I was under the impression I would only be charged actual cost of shipping. I brought this discrepancy to the attention of the proprietor and nothing more came of it.
Also I had ordered UHMW virgin 1 5/16" x 5 7/8" x 28 3/4" natural, and it arrived in a bowed condition: 1/4" at the center over the 28" span -- this bowing/warpage was not disclosed in the offering material. Fortunately my application did not need the entire length, so the bowing was not a defect rendering the piece unsuable for my intended application. Basically, if I had seen the piece live I would have concluded it was defective -- though, in this case, it did not matter since I was going to cut it into smaller pieces.
I inquired about an adjustment for the shipping overage and basically was ignored. I don't have a problem with people stating a minimum shipping charge, here I had concluded they only charge what they, in turn, are charged and that any savings as a result of consolidating multiple orders would accrue to my benefit. This misunderstanding coupled with the bowed UHMW causes me to post this. The other item I bought was as advertised. I'd probably buy from them again, but nail down details of shipping cost and condition.
I've picked up my pieces from a local scrap place that buys from a plastics distributor their left overs. But only one piece was used as a sled runner and it is too flexible for that.
Regarding the shipping charge issue, it actually is fairly common that "shipping" means "shipping and handling", ie, the shipper charges for some of the materials and labour necessary to ship the piece. I'm not saying it's right or wrong, just that it happens. I had planned a sliding scale of shipping charges based on the total of all sales, with the percentage that I cover going up with more sales. In the beginning, I have to start on the auctions (you have to accumulate so many points before you're allowed to open a store), so I have planned to ask customers to notify me in our preliminary emails after the sale if they have successfully bid on other items. I don't know how well that's going to work, but I'll try it and see.
Regarding the bowed/warped piece. First of all (not to split hairs too much), plastic does not warp; it bends. Bent pieces can be corrected about 95% of the time by putting them on a flat surface at room temperature and leaving them for a few days. Those that cannot be brought back are defective and I would certainly see that before it was shipped. Such a piece should not be shipped and if you got one of those, you should have got a refund. I put the above information in because it IS possible that the material was bent in transit. While it is possible to strap every piece to a hunk of wood, that's going to drive up the costs significantly, especially if you are shipping over a border. Most of the problems with bent materials are likely to happen with 1/4,
3/8 and 1/2" material.
I'm going to throw the subject open for discussion:
Assuming you are buying the thinner pieces, do you want to pay the extra cost to ensure flat material stays flat? (You're probably looking in the range of an extra $10)
If you're in Canada and close to one of their stores, they have additional assortments now that are only in the stores (no mail order) that are 4.5lb assortments with pieces that range from 16" in length to
30 -36 inches long. You may have to ask at the front counter (they haven't put them out yet) and insist that they look if they say they don't have it.(Some of the store people don't know that they have it yet)
UHMW (Ultra-High Molecular Weight) Polyethylene is a very slippery plastic that is usually used to reduce friction on sliding services when you make jigs for woodworking. In appropriately sized pieces, it makes good cutting boards because it does not absorb water like other plastics do. Since it does not absorb water, it does not absorb blodd on cutting boards, which makes them more sanitary when you wipe them down. As an aside, for anybody that has ever wondered why Nylon bushings squeak, it's because they absorb water. When they absorb water, they expand and jam against the shaft they are on. UHMW will not absorb water and therefore will not squeak. Back to the lesson - UHMW is also valued by woodworkers because it repels ALL Glues, including polycyanate and epoxy glues. I once asked an industry expert how to glue UHMW pieces together and he replied, "Use screws." (If you ever want to have some fun at a woodshow, take a couple of pieces of UHMW over to those guys that claim to have a glue that glues anything to anything and ask him to demonstrate on your pieces. It drives them crazy.) UHMW also has ENORMOUS crush resistance at room temperature ( approx 20 tons/square inch). So you cannot drive a nail through it unless you drill a pilot hole, and you must drill pilot holes for all screws or you'll snap them off. (UHMW will self thread with a pilot hole) UHMW does not have a lot of structural strength. If you're going to use it as a fence for your table- or bandsaw or for your router, either you need a really thick piece of you have to screw it to a piece of wood of metal. Woodworkers like UHMW because they can use all of their woodworking tools on it and it's really soft to cut and easy on their tools (You can literally carve it with a knife)
. Some specific cautions-
UHMW DOES NOT CHIP. Engrave this on your skull because it's extremely important. If you're drilling wood, the wood normally chips. UHNW doesn't. It tends to wrap around the spindle of the drill if you're using a Forstner bit, so don't be surprised when it does. I find that if you drill a bit at a time and then raise the drill bit, you will get chips that fall away from the work area normally. 2. If you are drilling large holes with a forstner bit, you want to move the bit through the plastic as fast as possible. If the drill bit spends a lot of time in the plastic, the plastic will start to melt and you will get crazing on the inside of the hole. 3. When you lathe UHMW, it does not chip. So if you're doing deep cuts you want to cut a bit, pull the tool back, then cut a bit. Then you'll get small chips that won't start wrapping around your spindle. 4. Table-sawing - Some thicker pieces of UHMW will start to curl back into themselves on long cuts, which will tend to bind the saw. You can prevent this by putting small wedges in the end of the boards to keep them open. 5. Bandsawing - See # 4 above in spades. A friend of mine put an impressive kink in his bandsaw blade when he tried to crosscut a 7" diameter piece by grabbing either end and pushing it through the blade. He made it about 3/4's of the way through when the ends of the plastic came together, grabbed the blade and stopped it dead in about 1/10th of a second. If you have to resaw by bandsaw, use wedges. 6. Routing. - No special problems because routers make their own chips. I advise against using router mats because the plastic is so slippery. 7. Surface planing/jointing - Again, no special problems.
A special note of caution. If UHMW ignites, it smells like candles buring, but the drippings are NOT wax. They will burn through your skin right to the bone and keep buring until the fuel is exhausted. Hurts like hell and you're talking 3rd degree burns. So be careful.
I put it on a flat surface at room temperature and add a weight at the center of the bend. Since I typically use it as a face material for a fence or jig, most of the time I don't bother flattening prior to attaching it to the wood. I would not pay extra.
I have machined UHMW,NYLON,DELRIN,HDPE,POLYCARBONATE every day for 15 years. It is not uncommon for UHMW to come from the factory with a little warpage, especially close to the edge of the sheet. UHMW sheets come to us from 1/8 thk thru 4" thk and are either 48 x 120 or 60 x 120 size.
We cut it with a CNC Schelling panel saw 18" dia blade 32 hp. I buy the blades from Woodworker Supply and order Freud heavy body wood rip blades , actually P/N LM71M 16" dia 28 teeth works very well and are dirt cheap at
80.00 ea..
If you use a fine tooth blade on UHMW the shavings will be very stringy and get wraped around things. Blade or cutters must be very sharp or any plastic material will heat and induce some warpage possible closing behind the blade as you cut it.
UHMW can kick back out of a saw worse than wood, before we got the CNC saw workers would get hit from pcs coming out of the UNISAW at warp speed usally hitting them in the family jewles. Never bring the cut pc over the saw blade because if you drop it (very slippery material)on the blade UHMW is soft and the blade grabs it very well and throws it back at you, Stand slightly to the left so when this happens to you it will miss you and just put a hole in the wall instead of you.
Use coarse tooth blade for UHMW use sharp blades or you could get hurt.
I'm rambling again sorry UHMW has a tolerance of +/- 10% for thickness . This means .75 thk material can vary +.075 to -.075 from the stated .75 anywhere in this sheet. I rarely see a sht that is perfictley flat we use the next higher thickness and mill or route the surface on CNC routers and CNC mills to get flat parts.
We only sell to commercial accounts unfortunately and we throw cutoffs of this material in the garbage each and every day. We have collected 4ft x 4ft x 4ft containers of it and tried to sell it to recyclers it but its not worth the freight cost ,it would cost us more than they will pay per pound to send it to them.
If your using it for a fence liner on the table saw you could joint and plane it to get it flat. It does joint and plane very well, again use sharp blades. The chips tend to get stuck in the jointer so have the compressed air gun handy and have someone blow on the cutter head while you push the pc over the jointer. USE a push block and take light cuts.
I will sign off now as this has stretched out longer than I intended.
Better yet, inform your customer of the risks and offer both services, educating your customer as to the options and letting them make the decision is a win-win situation, for you it should just be a matter of setting the appropriate price/handling charge.
Eric - If you're going to be ripping a lot of this stuff, I suggest thin-kerf blades. I use 10" 24-tooth Freud red blades for thin material. Above an inch in thickness, you'll want to be getting flat-top teeth and get as agressive a ripping profile as you can find.
Eric - He's absolutely right about UHMW getting thrown by saws. I used to get it thrown at me all the time (Usually in the gut). I have found the best way to beat that is to cover the entire saw face with a sheet of UHMW (I use 3/4") and I have designed sleds and special fences that sit on top of the sheet. Since then the number of times the saw has thrown pieces back to me is down near zero.
Eric - I have noticed a lot of material benefits from being surface planed. We surface plane thicker materials if they have scratches or imperfections.
Eric - That brings up a good point - We only use surface planers that have back chip ejection ports. If your planer has a side ejection port it could get clogged very quickly. I find that you have to check the spaces beside the rollers frequently, as some of the material can get caught there. As far as jointers go, it's going to help if your jointer has a clear, straight path to eject the chips. I've recently bought a Jet jointer with a stand and I'm going to have to remove the stand and make another one because this thing has a little 4" hole to eject chips off the side. Sucker's going to clog in about 10 seconds.
Did that include packaging and handling costs? You have to add those in, you know. It costs money to put it in the box, at the very least, plus the cost of the box itself, the labeling, etc. I have no idea what would be reasonable in your case since I don't know anything about the size and packaging, but you can't forget those costs as well.
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